title: Receptor structure in the bacterial sensing system.
abstract: The primary receptors for aspartate and serine in bacterial chemotaxis have been shown to be the 60,000-dalton proteins encoded by the tar and tsr genes. The evidence is: (i) overproduction of the tar gene product at various levels by recombinant DNA techniques produces proportionate increases in aspartate binding; (ii) aspartate binding copurifies with [3H]methyl-labeled tar gene product; (iii) antibody to tar and tsr protein fragments precipitates a single species of protein (60,000 daltons) which retains binding capacity and [3H]carboxymethyl label. Partially purified tar gene product can be reconstituted into artificial vesicles and retains aspartate binding and aspartate-sensitive methylation and demethylation. These results show that the aspartate and serine receptors are transmembrane proteins of a single polypeptide chain with the receptor recognition site on the outside of the membrane and the covalent methylation site on the inside.
mesh_terms: D001224:Aspartic Acid; D001426:Bacterial Proteins / Q000302:isolation & purification*; D002633:Chemotaxis; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000502:physiology; D005796:Genes; D046911:Macromolecular Substances; D011485:Protein Binding; D011955:Receptors, Drug / Q000302:isolation & purification*; D012694:Serine
chemical_list: D001426:Bacterial Proteins; D004274:DNA, Recombinant; D046911:Macromolecular Substances; D011955:Receptors, Drug; D001224:Aspartic Acid; D012694:Serine